Clamp tightener



E. BIBA, JR

April 4, 1950 CLAMP TIGHTENER Filed Jan. 14, 1946 clamp embraces ordirectly engages.

Patented Apr. 4, 1950 UNITED STATES PATENT OFFICE CLAMP TIGHTENER EdwardBiba, Jr., Cicero, 111., assignor to Wittek Manufacturing 00., Chicago,111., a corporation of Illinois Application January 14, 1946, Serial No.641,131

3 Claims. 1 I

This invention relates generally to clamp tighteners and has particularreference to an improved yieldable clutch-type tighteninginstrumentality.

There are various clamps, of the hose clamp type, wherein a rotatableelement, usually a screw, in one way or another draws a flexible metalband tightly about the object which the When a wrench or the like isused to turn the screw in tightening the clamp,- the clamp elements arefrequently unduly stressed and the hose or other object gripped soforcibly as to cause damage to the tightening instrumentality or to theclamp band.

The object of the present invention is to provide simple, novel andeffective means to overcome the hereinabove-stated disadvantages and toprevent a clamp from exerting undue pressure on an object embracedthereby, while at all times permitting adequate tightening of the clamp.

In carrying out my invention, I provide the rotatable tightening memberof a clamp with .a part which is adapted to be engaged by a wrench orother tool and which acts as an integral part of the tightening memberexcept when the resistance to turning offered by the latter passes apredetermined safe maximum. When this limit of safety is reached, thewrench-engaged part, which may be termed the actuator, automaticallyoverruns the screw or other rotatable tightening member; the tighteningmember standing still and no further movement of the wrench in thedirection to tighten the clamp having any effect on the same.-

Viewed in one of its aspects, therefore, the present invention may besaid to have for its object to provide a rotatable clamp tighteningmember with a simple, novel, and reliable actuator that prevents theturning of such member farther than required to produce the desiredtightness of the clamp of which it forms a part.

The various features of novelty whereby the present invention ischaracterized will hereinafter be-pointed out with particularity in theappended claims; but, for a full understanding of the invention and ofits objects and advantages, reference may be had to the followingdetailed description taken in connection with the accompanying drawing,wherein:

Fig. 1 is an end view of a well known type of clamp, to the screw memberof which the present invention has been applied;

Fig. 2 is a section on line 22 of Fig. 1;

Figs. 3 and 4 are sections taken, respectively, on lines 3-3 and 44 ofFig. 2;

Fig. 5 is a perspective view showing the three parts of the screw deviceseparated from but in axial alignment with each other, ready forassembly;

Fig. 6 is a perspective view of a slighlty modie fied form of spring foruse in the screw device;

Fig. 7 is an elevational view of a screw device in which the newfeatures differ somewhat in construction from the corresponding parts inthe preceding views;

Fig. 8 is a section on line 88 of Fig. 7;

Fig. 9 is a view similar to Fig. 5 illustrating the modified form ofFigs, '7 and 8;

Fig. 10 is a section on line lfi-I0 of Fig. 8; and

Fig. 11 is a section on line Hll of Fig. 9.

Referring to Figs. 1-5 of the drawing, 15 represents any usual orsuitable screw or other rotatable member for tightening a clamp; theclamp Iii shown in Fig. 1 being a well known type of hose clamp andbeing intended simply to. be i1- lust-rative of clamps in general andconsisting of essential elements, such as, the flexible band 38 having acircular medial portion 39 and substantially straight convergingextensions 40 terminating in overlapped ends 4! secured to a nut 42 withwhich the tightening screw I5 has threaded engagement; the end IE of thetightening screw 15 being rotatably connected with the bridge 43. Thereis a round enlargement or head I! on the outer end of the screw. Fittedover this head I! is a cap member l8 having in the lower end an open,cylindrical chamber IS in which the head IT on the screw is a rotatablefit. This chamber I9 is considerably deeper than the thickness of thehead and opens into a smaller chamber 20, conveniently square in crosssection, extending well up into the cap member ill at the centerthereof.

A little post 2 l, of square or other noncircular shape in crosssection, fixed to and preferably integral with the head l'i, rises fromthe center of the head I! into chamber 20. The post 2;! is not as longas the depth of chamber 20 and is also smaller in cross sectional areaso to leave a substantial clear space in the chamber around the post 2!.Set on top of the screw head I? is stiff spring element 22 in the shapeof an inverted U that has its arms 22 positioned on opposite sides ofthe post 2|.

The U-shaped spring element 22 is wider than the post 2! andsufficiently wide to be interlocked with the cap, in chamber 20, againstrelative rotary movements between the same and the cap. The arms of theU are bent so that each presses against the corresponding side of thepost. In the arrangement shown, the arms are bowed and are closesttogether at their free ends.

After the spring 22 has been slipped on the post 2| and the cap 18 hasbeen placed in position to enclose the head l2, post 2! and spring 22,the marginal portion at the lower end of the cap is is flanged or swagedinwardly, as indicated at 23, to fasten the cap l8 to the screw I5; thecap it being thus held against separation from the screw [5 althoughbeing rotatable thereon. The cap I 8 may have at the top a thumb pieceor part 24 4 to produce thereon .two little radial troughshapedprotuberances 34 or up-set deformations spaced apart on opposite sidesof the hole 33. Each disc also has, at two diametrically opposed points,little ears 35 projecting from the edge in the plane thereof. Each ofthe walls surrounding chambers 33 and 3| contains a pair ofdiametrically opposed notches 36, 36 and 37, 31, respectively, in whichthe ears on the corresponding disc are seated. Thus one disc 32 isinterlocked with the screw head 27 and the other with the cap 23, eachdisc 32 being held against rotation relative to the element with whichit is so interlocked.

The chamber 3i in the screw head 21 has a. depth which is preferablyonly slightly deeper than the thickness of the disc therein, however,the chamber 30 in the cap 23 is of sufficient depth to have its innerflat circular wall in engagement with the protuberances 34 of the disctherein.

Normally, during tightening of the screw 26,

, the pairs of protuberances 34 of the two discs 32 adapted to beengaged by a wrench to turn the same.

The parts are so proportioned that the operative connection between thecap i8 and the screw l5 is, in effect, a rigid one as long as the screwdoes not offer more than the desired predetermined maximum resistance toturning with the cap. When the resistance exceeds such desired maximumvalue, the spring 22 and the post 2| become cooperating camming or slipclutch members functioning to spread the arms 22 of the spring 22 farenough apart to enable the spring 22, and therefore the cap 18, torevolve about the post 2!. So, in order to insure that the clamp shallnever be tightened beyond a desired point or extent, the spring 22 needonly be designed to yield and allow the cap l8 to overrun the screw l5when such point is reached. The extent of the desired applied clampingpressure may be varied for different clamp uses by the use of springsvarying in thickness and widths, hence, any desired maximum clampingpressure may be obtained by the use of proper width and thickness ofspring material.

Instead of having the arms 22 of the spring bow oppositely outwardly atthe middle as in the form just described, the curvature may be in theopposite direction. Thus, the spring 25, shown 1 in Fig. 6, has its arms25 closest together at the middle, or, at least, at some distance fromtheir free ends.

In Figs. '7 to 11 inclusive there is shown a construction wherein bothcamming or clutch members that afford a yieldable driving connectionbetween the cap and the screw are springs. In this form of the device,also, the screw 26 has a head, indicated at 21, over which a cap 28 isset; the marginal portion at the lower end of the cap 28 being swaged toproduce an inwardly extending flange 28 that underlies the head 21.Chamber 30 in the cap 28, corresponding to chamber E9 in the other form,is shallow and registers with a similar, still shallower, chamber 3| inthe top of the screw head 21. Within these registering chambers are twolike discs of preferably spring metal or at least one of the discs beingof spring metal. These discs are designated by the numeral 32 and are sodeformed that, when they are laid one upon the other and turnedrelatively to each other, the portions in the normal planes thereof arecaused to move away from each other. In the arrangement shown, each disc32 has a central hole 33 and is crimped along a diameter are nestedtogether and because one of the discs has its opposed ears 35 within thenotches or seats 36 of the cap 28 and theother disc has its ears 35within the notches or seats 36 of the cap 28 and the other disc has itsears 35 within the notches or seats 31 of screw head 21, the discsrotate together and with the members in which they are so seated andthrough the interlocking operative connection established by theinterlocked nested protuberances 34 a rotation of the cap 28, by awrench or suitable tool, is transmitted to the screw 26.

The discs and their nested rotuberances are so proportioned that theoperative connection between the cap 28 and the screw 26 is, in effect,a rigid one as long as the screw 26 does not offer more than the desiredresistance to turning with the cap 28. When the resistance exceeds suchdesired maximum value, the protuberances 34 will be automaticallydisplaced from their nested positions so that the cap 28 will overrunthe screw 26 because the disc within the cap 28, because of itsresiliency, will slidably rotate over the disc seated in the screwhead21.

The combined depths of chambers 33 and 3| is such that when the discsare within the same, in nested relation to each other, they touch boththe floor and the ceiling of the composite chamber. Then, when a tool isapplied to the cap to turn the same, the screw is driven through themedium of the nested protuberances on the discs. These protuberances actas cams, those on one disc that are seated in the troughs of theprotuberances on the other tending to push themselves out of suchtroughs as soon as the screw begins to offer resistance to the effort ofthe cap to 'turnit. When such resistance reaches the safe point in thetightening of the clamp, the pressure on the protuberances become sogreat that a deformation of the discs sufiicient to permit theprotuberances on one to snap past those on the other occurs; the screwthereafter remaining stationary even though the cap should continue tobe turned.

It will thus be seen that I have provided a very simple means forpositively guarding against damage through the application of too greata force in the tightening of a clamp wherein the tightening is done by arotating element, usually a screw.

While I have described with particularity the various features of myinvention embodied in the illustrations in the drawing, I do not desireto be understood as limiting myself to the precise details thusillustrated and described, but intend to cover all forms andarrangements that'come within the definitions of my inventionconstituting the appended claims.

The invention is shown and described for illustrative purposes asapplied to a hose clamp tightening screw but it is obvious that myinvention may be readily applied to other tightening elements or devicessuch as screws for securing various members other than a clamp band.

I claim:

1. A tightening instrumentality including a screw having at one end ahead; a wrench-engageable cap; means providing interengagement of saidcap with said head permitting rotation of said cap relatively to saidhead but preventing displacement of said cap from said head; twocooperating clutch members, one of said clutch members being a post onsaid head, non-circular in cross-section and smaller in cross-sectionalarea than the interior of said cap, the other clutch member being aU-shaped spring that rotates with said cap and has curved arms engagedwith opposite sides of and gripping the post at points in the arms whichare normally closest together, said spring permitting relative turningmovements between the screw and the cap when the resistance offered bythe screw to turning exceeds a predetermined value.

2. A tightening instrumentality including a screw having at one end ahead; a wrench-engageable cap; means providing interengagement of saidcap with said head permitting rotation of said cap relatively to saidhead but preventing axial displacement of said cap from said head; twocooperaitng clutch members, one of said clutch members being a post ofnon-circular cross-section on said head and the other of said clutchmembers being a U-shaped spring within said cap that normally intightening operation rotates with said cap and has oppositely outwardlybowed arms the free ends of which engage with opposite sides of saidpost, said spring permitting relative turning movements between thescrew and the cap when the resistance offered by the screw to turningexceeds a predetermined value.

3, A tightening instrumentality including a screw having at one end ahead; a wrench-engageable cap; means providing interengagement of saidcap with said head permitting rotation of said cap relatively to saidhead but preventing axial displacement of said cap from said head; twocooperating clutch members, one of said clutch members being a post ofnon-circular cross-section on said head and the other of said clutchmembers being a U-shaped spring within said cap that normally intightening operation rotates with said cap and has oppositely inwardlybowed arms Which are closest together at their medial portions whereatthey engage with opposite sides of said post, said spring permittingrelative turning movements between the screw and the cap when theresistance ofiered by the screw to turning exceeds a predeterminedvalue.

EDWARD BIBA, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,468,322 Odom Sept. 18, 19232,409,545 Cornwell Oct. 15, 1946 FOREIGN PATENTS Number Country Date749,550 France 1933

